Preserving biodiversity requires more than species conservation

10/04/2019

Among global environmental issues, climate change comes first to most peoples’ minds. Biodiversity loss is likely to come second; however, the connection between these two is largely ignored. More importantly, the effects of changes in biological diversity on ecosystem processes and even on regional climate are also ignored or misunderstood.

Climate change is fairly straightforward to assess and present, compared to changes in biodiversity. However, it is much more difficult to demonstrate causes and to predict effects of climate change. Likewise, the causes for changes in biodiversity and their foreseeable consequences are also considerably more contentious.

The Convention for Biological Diversity, drawn up in Rio in 1992, defined biodiversity as “the variability among living organisms from all sources including […] diversity within species, between species and of ecosystems”. The first two are commonly understood, respectively, as genetic diversity and species diversity. The inclusion of ecosystems, while encompassing the variety of terrestrial and aquatic landscapes and habitats, does surely imply that these are to be conserved as functioning entities, much as species should be conserved as populations of living organisms in their natural habitats. Thus, the Convention for Biological Diversity extended its goals beyond the conservation of individual species or their genetic variety, to also embrace the maintenance of functioning ecological systems.

Decades before the CBD, conservation movements were organized to recognize species at risk and prevent their extinction. Public opinion, private institutions and governments were mobilized to provide resources and legal bases for conservation actions aimed at these species. The International Union for the Conservation of Nature, founded in 1948, has been producing a Red List of Threatened Species since 1964. This list is a reference standard for the CBD itself, for the GEF (the Global Environmental Facility, the chief environmental financing instrument of the World Bank) and for many other national and international agencies and NGOs.

Red Lists do not give equal treatment to all groups of living organisms. Nor could they. There are dramatic differences in the degree to which species have been described, ranging from birds - in which less than 5% of new species are expected to be discovered and described worldwide - to most invertebrates - in which it is likely that 80% to 95% of species have not been described by scientists, or not even collected. The condition is even worse for microscopic groups, such as bacteria, in which the classical concept of species has to be modified or abandoned.

The geographical extent of our knowledge of biodiversity is also very uneven. It is fairly comprehensive for Europe and North America, but much less so in other continents. In the open ocean and on land there are huge unknown domains, such as the canopy of tropical forests.

It is no surprise, therefore, that assessments of changes in biological diversity rely to a large extent on some groups, for which more and better data are available: terrestrial vertebrates (birds, mammals, reptiles and amphibians), flowering plants, and some groups of invertebrates such as butterflies, ants, bees, or large mollusks. Although these assessments emphasize the proportion of species in each group that are at risk, public attention is restricted to certain species that are highly publicized and cherished.

But here’s the problem. Major environmental analyses and policy proposals nowadays emphasize the vital importance of maintaining the integrity and functioning of entire ecological systems. In this regard, many inconspicuous and little-known organisms are functionally very important; for instance, bacteria, fungi and free-living worms in the soil are essential to the complex circulation and supply of nutrients to plants and animals. This raises a number of issues, two of which are highlighted here:

1) Can these groups of functionally important organisms – or, more significantly,  the environmental processes that they drive – be monitored solely by assessing larger organisms?

To a certain degree, the diversity of vertebrates and especially of plants does denote the integrity of ecological systems and processes of which they are part. However, they are far from sufficient for this. More informative and reliable assessments can only be obtained by focusing directly on groups that have known key roles in the ecosystem functions of interest: nitrogen-processing bacteria or earthworms in the soil, pollinating insects, and so on.

2) Are conservation resources concentrated on charismatic species and groups, to the point of impairing the research and management of functionally critical components of the planet’s biota?

Charismatic species do attract sympathy and support from the public, which induces backing from governments and corporations. It is often argued that they are effective “umbrella species”, whose preservation will protect other species and even entire habitats. This has equivocal consequences, to say the least. Consider that environments that harbor a worldwide favorite, such as the panda, will receive heavy and sustained support; meanwhile, the majority of imperiled environments, for lack of a champion species or visibility in the media, will be uncared.

Given the shortage of resources for environmental action, concentration on charismatic organisms inevitably compromises investment in other functionally important groups. Indeed, the entire allocation strategy of financial and human resources to the conservation of environments and natural resources should be reconsidered. However, this needs to be preceded by a clear understanding that vital ecological functions depend on recovering and managing entire suites of hardly visible species and, even more, on sustaining the biological and physical interactions that orchestrate the functions themselves.

It would be pointless as well as naïve to propose a radical diversion of conservation funds to the recovery and maintenance of ecosystem processes. Charismatic species and groups will retain the public’s affection and therefore their branding value to institutional sponsors. But it seems reasonable to expect that, by now, components of biodiversity involved in the maintenance of ecological processes and services required by humans should receive at least equal attention and effort. They already do so in global policy designs and goals, but these remain largely as statements of principle.

Key biodiversity components of ecosystem processes should be routinely included in the entire spectrum of environmental initiatives: inventories, impact assessments, studies to subtend management and restoration actions. They should not be an occasional add-on, or restricted to some particular interactions, such as the  recent worldwide pollinator initiative. Conserving biodiversity entails far more than salvaging fragile species from risks caused by human activity; it is about preserving organisms and processes that are vital to the present quality and future prospects of human life on this planet.

reagissez !

Ajouter un commentaire